Rationale: Impaired skeletal muscle function contributes to exercise limitation in patients with chronic obstructive pulmonary disease (COPD). This is characterized by reduced mitochondrial adenosine triphosphate generation, and greater reliance on nonmitochondrial energy production. Dichloroacetate (DCA) infusion activates muscle pyruvate dehydrogenase complex (PDC) at rest, reducing inertia in mitochondrial energy delivery at the onset of exercise and diminishing anaerobic energy production.
Objectives: This study aimed to determine whether DCA infusion enhanced mitochondrial energy delivery during symptom-limited maximal exercise, thereby reducing exercise-induced lactate and ammonia accumulation and, consequently, improving exercise performance in patients with COPD.
Methods: A randomized, double-blind crossover design was used. Eighteen subjects with COPD performed maximal cycle exercise after an intravenous infusion of DCA (50 mg/kg body mass) or saline (control). Exercise work output was determined, and blood lactate and ammonia concentrations were measured at rest, 1 and 2 minutes of exercise, peak exercise, and 2 minutes postexercise.
Measurements and main results: DCA infusion reduced peak blood lactate concentration by 20% (mean [SE]; difference, 0.48 [0.11] mmol/L, P < 0.001) and peak blood ammonia concentration by 15% (mean [SE]; difference, 14.2 [2.9] mumol/L, P < 0.001] compared with control. After DCA, peak exercise workload improved significantly by a mean (SE) of 8 (1) W (P < 0.001) and peak oxygen consumption by 1.2 (0.5) ml/kg/minute (P = 0.03) compared with control.
Conclusions: We have shown that a pharmacologic intervention known to activate muscle PDC can reduce blood lactate and ammonia accumulation during exercise and improve maximal exercise performance in subjects with COPD. Skeletal muscle PDC activation may be a target for pharmacologic intervention in the management of exercise intolerance in COPD.